The present invention relates generally to an article retaining arrangement and, more particularly to an article retaining arrangement utilizing various combinations of expansion fasteners, article engaging portions and surface retaining portions as used with drywall or similar panels or walls in building construction.
Numerous different article retaining arrangements are known. Such devices are often used to retain pictures, ornaments, hooks or other articles directly to the interior building wall. Such walls are typically nailed or glued to skeletal frame members of the building and subsequently the gaps between adjacent sheets are taped and covered with paint or wallpaper. Once so covered, it is usually difficult to locate the underlying frame members. Thus, article retaining arrangements tend to rely only upon the support strength of the drywall board or wall panel element itself.
Two general types of drywall expansion fasteners are used: Those that require prior drilling or punching through the wall to permit fastener insertion, and those that are self-penetrating in that they may be directly hammered, punched or screwed into the wall. The latter type of fasteners are typically referred to as "drive-in fasteners" and tend to be preferred since they permit quicker installation. However, prior drive-in fasteners frequently could not support the same loads as fasteners using preformed holes since the act of penetrating the wall with drive-in fasteners tends to create a "blow out" in the back side of the wall.
Blow outs are believed to result from the fact that prior drive-in fasteners merely push the wall material aside and forward during their penetration. This displaced material appears to weaken the adjacent wall structure and creates a larger opening at the side of the wall opposite the initial penetration of the fastener. A typical blow out situation is shown in FIG. 1. The fastener 10 (shown only in part) penetrated wall 12 from left to right. The initial penetration opening has a width of I. The opening created by the blow out has a significant larger width B. As a result, load support within the wall for the fastener is available only for the distance L where the width of the hole closely corresponds to the width of fastener 10. As a general rule, the larger L becomes, the more load the fastener can support.
Blow outs can also be a problem for fasteners using preformed holes, but, for example, careful drilling can minimize the occurrence of blow outs. Unfortunately, such drilling is time-consuming and, especially where a large number of fasteners are needed, can result in significantly higher installation costs.
The installation costs are also effected by the price of the article retaining arrangement itself. To retain the fastener in the wall, a portion of the fastener which has penetrated the wall often expands so as to prevent the fastener from being withdrawn from the hole created in the wall. The expansion can occur within the hole or past the hole on the back side of the wall. Mechanisms which create this expansion are sometimes elaborate and can significantly increase the fastener's production costs.
Typically, it is also important not to create bulges in the wall surrounding the fastener when expanding the fastener to retain it in the wall. These bulges can be unsightly and can structurally weaken the wall. Thus, stress control and fastener expansion can be critical.
Insertion elements for controlled fastener expansion are often expensive and require specially formed parts. Some prior fasteners have been constructed to reduce these costs by permitting expansion adjustment through ordinary screws provided by the installer. Unfortunately, the torque required to insert those screws is frequently so high that the installation of a number of these fasteners becomes overly tiring and/or time consuming. In addition, it is common that a particular fastener of that type will accept only one screw size. On the other hand, fasteners which are adjustable by extremely low threading torque sometimes give no indication of when the fastener has bottomed out and is fully engaged wtih the back of the wall. As a result, the installer may not realize when to stop threading and may cause serious damage to the wall, if threaded too far, or inadequately secure the fastener, if not threaded far enough.
Since threaded elements requiring rotation have been typically used, it is normally necessary to provide anti-rotation fins or ribs in the fastener in order to allow the screw to be rotated and inserted into the fastener. Such fins often require a larger hole to be made in the drywall than would be necessary if an insertion element could be used which does not require rotation for installation.
It is often necessary to insert a screw so that its head is flush with the fastener in order for the expansion to occur. Since there is no other stop provided on a typical screw, it is difficult to determine when the screw has been adequately inserted to engage the expansion elements while still providing enough of an extension form the wall to retain articles such as pictures, ornaments, hooks or other items.
Applicant's copending U.S. patent application Ser. No. 070,897 filed July 8, 1987, describes in detail a preferred solution to many of these problems and concerns. To the extent not explicitly set forth herein, the disclosure of that application is incorporated by reference. The present application is directed further to improving upon the typical usage of applicant's prior invention, particularly through improvement of the article engaging and fastener expansion features.
Specifically, it has been found to be desirable to minimize the effort necessary for an insertion element to expand the fastener to secure it to the wall. At the same time it is desirable to maximize the force necessary for removal of that insertion element from the fastener up to a point where inadvertent removal does not occur under normal usage. Beyond that point removal of the insertion element should be facilitated to avoid unintended destruction of the fastener and/or wall surface. Preferably the insertion element could enter and expand the fastener by uni-directional force, similar to the pounding of a nail by a hammer.
Further, it has been found to be desirable to provide increased load support for articles retained on the fastener. At the same time, it is desirable to minimize the number of individual elements necessary for attachment of decorations and utility articles to a wall surface. Among other factors, these two objectives can be important in cost reduction, ease of assembly and security of installation.
It is, therefore, an object of the present invention to provide an improved article retention arrangement which overcomes limitations of previous article retention arrangements.
In addition to the objectives and purposes of applicants above-noted previous fastener invention, it is another object of the present invention to provide an inexpensive and reliable article retention arrangement which is readily secured to a wall or ceiling.
Still a further object is the provision of an article retention arrangement with minimal actuation effort requirements and increased actuation retention up to a predetermined level so as to minimize accidental disassembly of components.
Still a further object is a provision of an article retention arrangement having improved load support.
Still a further object is the provision of an article retaining arrangement having simplified assembly requirements and having features readily incorporable into decorations and utility articles to be mounted to walls or ceilings.
These and other objects of the present invention are attained by the provision of an article retention arrangement utilizing a driven-in expansion fastener having a generally cylindrical, hollow body with a tapered end formed from an angular truncation of the body. The body is reinforced by one longitudinal rib so as to permit drive-in penetration from the tapered end even if the fastener is formed from plastic materials. The fastener is retained within the wall by at least one pair of hinged flanges which expand circumferentially in response to the installation of an insertion element within the hollow portion of the body. The insertion element engages an inclined surface within the body to cam the expansion flanges circumferentially outward. The expansion flanges engage the back surface of the wall while the longitudinally slit portion of the body expands within the hole created by drive-in penetration.
The present invention avoids blow outs by creating a clean cut through the drywall with the tapered end and receiving the cutout debris within the fastener as the penetration is made. Thus, destructive stress within the wall beyond the penetration hole is minimized. The fastener and/or the insertion element can be molded from a self-lubricating nylon or polyester so as to minimize the effort required to install the insertion element. Installation is, for example, completed when an initial enlarged portion of the insertion element is flush against a shoulder portion of the expansion fastener extending from or on the front surface of the wall. Installation of the insertion element primarily causes the hinged flanges to move circumferentially outward along the back surface of the wall, rather than into it. Thus, bottoming out the insertion element on the fastener shoulder avoids creating bulges and undesired expansion stress within the wall.
The insertion element preferably includes an enlarged head projecting from the fastener when the insertion element is fully installed within the fastener. This head is spaced apart from the fastener and the wall by a reduced diameter portion. Thus, articles can be mounted to the wall by direct application to the insertion element. Alternatively, an article engaging element containing an angular slot for slidably receiving the installation element may be utilized to removably secure articles such as hooks, curtain rods, soap dishes, towel bars, storage racks or other items. This article engaging element can also be integrally formed within such articles. Alternatively, the fastener itself can be formed with an enlarged head extending from the shoulder and spaced apart from the wall surface which is directly receivable within the slot of said article engaging element.
Further, the insertion element includes a series of truncated conical sections formed so as to facilitate uni-directional insertion into the fastener and restrict removal of the insertion element. That element is also dimensioned with respect to the fastener to have a close fit which increases load support. Similarly the slot of the article engaging element is dimensioned and inclined so as to improve load support.
Other objects, advantages and novel features of the present invention will become readily apparent upon consideration of the following description of preferred embodiments in conjunction with the drawings.